In order to develop efficient visible light photocatalysts for air purification, three dimensional (3D) (BiO)(2)CO3/BiOI (BOC/BOI) solid solutions were synthesized by a template free method at room temperature. This environment benign route could avoid high temperature and reduce the production cost. The results indicated that the as-prepared hierarchical nanocomposites samples assembled with 2D nanosheets were solid solutions. The aggregation of nanosheets led to the formation of 3D hierarchical porous architecture. For the (BiO)(2)(CO3)(x)(I-2)(1-x) solid solution with x = 0.5, 0.75, 0.95, the samples have down-lowered valence band (VB) and up-lifted conduction band (CB) in contrast to (BiO)(2)CO3. Compared with (BiO)(2)(CO3)(3.14 eV), the (BiO)(2)(CO3)(x)(I-2)(1-x) solid solution showed narrowed band gaps from 1.89 to 2.68 eV which are suitable for visible light excitation. The 3D (BiO)(2)(CO3)(x)(I-2)(1-x) solid solutions displayed efficient photocatalytic activity and high durability toward photo-oxidation of NO (600 ppb) in air. The large surface areas, hierarchical structure, and tailed band-gap structure contributed to the efficient photocatalytic oxidation ability of (BiO)(2)(CO3)(x)(I-2)(1-x) solid solution. As NO has very low solubility and NO2 has a large solubility in water. A high NO to NO2 conversion ratio is beneficial for NOx removal by aqueous absorption. The photo-oxidation products can be readily and inexpensively removed by alkaline aqueous absorption. This work could provide new insights into the design, synthesis and environmental application of hierarchical nanocomposites photocatalysts. (C) 2014 Elsevier B.V. All rights reserved.